Interlocks for folding box corners



Dec. 2, 1969 c. J. PIERCE, JR 3,481,526

INTERLOCKS FOR FOLDING BOX CORNERS Filed Aug 2. 1968 INVENTOR. C/wszer J Pie/c6, Jn

United States Patent 3,481,526 INTERLOCKS FOR FOLDING BOX CORNERS Chester J. Pierce, Jr., Palo Alto, *Calif., assignor to Kliklok Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 2, 1968, Ser. No. 749,649 Int. "Cl. B65d 5/26 U.S. Cl. 22935 5 Claims ABSTRACT OF THE DISCLOSURE A glueless interlock is provided in which an internally disposed tongue-forming engagement slot in a corner flap articulated to one box wall panel at a corner fold line is insertable into an insertion slot in another wall panel. The other wall panel has an angular tongue-forming engagement slot in it between the insertion slot and the box corner. The tip of the tongue acts as a safety catch for interengaging edges of the two engagement slots when snapped past the edge of the engagement slot in the flap.

The present invention provides improvements in glueless corner locks for folding boxes of the known style in which a corner flap articulated to one wall panel along a corner fold line is inserted into a first slot in another wall panel meeting the one panel at a box corner, and in which an edge of an internally disposed engagement slot in the corner flap is brought into locking engagement with an edge of an internally formed slot in the other wall panel, the engagement of edges being then secured by a lug on either flap or panel, which lug is snapped past an edge in the panel or flap, respectively.

An interlock of known design and of the aforesaid style provides in the wall panel an engagement slot which is separate from, and runs parallel to, the insertion slot, both slots being straight-linear cuts.

The engagement of such an interlock is attended by two difficulties. The first difiiculty is experienced when the engagement edge which comprises the locking lug overtravels the edge of the engagement slot past which the lug must be snapped in order to set the lock. In such a case the elastic lug is not the only element which opposes the snapping of the edges one past the other, but the entire slot edge on both sides of the lug seats on the board surface adjacent the other engagement slot and the result is merely the joint deflection of the slotted flap and the slotted panel. This prevents movement of the lug into locking position.

A further difliculty is caused by the tendency of both panel and lock flap to bulge out because flap or panel portions bordered by a straight out or slot are relatively stiff.

The improvements disclosed herein provide for a configuration of the respective slots which results in the formation of a readily deflectable tongue in the wall panel, the point of which may be flexed with relatively little force past the edge of the engagement slot in the lock flap and which, by reason of its configuration, does not tend to seat on the surface of the lock flap when the wall tongue is deflected towards the outside of the box for the boxes for different purposes, no one specific form can properly be called a preferred embodiment.

The invention also resides in certain new and original features of construction and combination of elements and configurations herein set forth and claimed.

Although the charatceristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its

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objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of the disclosure.

, Certain of the figures will be referred to as combination box end, elevational and blank plan views. These figures show a locked-up box corner at the left in elevation and show the blank portion for the right box corner at the right. The blank portion is shown in plan View and appears as if a portion of the blank bottom and of the box side panel had been torn from the finished box and laid flat.

FIG. 1 and 2 are combination views of a box end in elevation and a blank in plan view employing locking elements of different configurations; and

FIG. 3 is a representative sectional view illustrating the relative location of the several panels and edges, the section being taken on line 33 in FIG. 2.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be primarily descriptive and generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

The drawings accompanying, and forming part of, this specification disclose certain specific details of construction for the purpose of explanation of broader aspects of the invention, but it should be understood that structural details may be modified without departure from the principles of the invention and that the invention may be incorporated in other structural forms than shown.

Referring to FIG. 1, the folding box A comprises a bottom panel 11 to which side panels 12 and an end panel 13 are articulated along side and end fold lines 14 and 15, respectively. Corner lock flaps 16 are articulated to the side panels 12 along corner fold lines 17.

Adjacent each corner the end wall panel 13 comprises an internally disposed angular insertion slot 18 which forms an internal wall tongue 19 which is directed to wards the proximate box corner.

Each corner fiap has a first engagement slot in it comprising two substantially straight-linear portions 20, 21 and a bowed portion 22 therebetween.

As seen from the left hand portion of FIG. 1, the corner flap 16 is insertable into the insertion slot with the result that the edge of the internal tongue 19, which faces the corner, is exposed as it overlies flap 16.

The wall panel has a further engagement slot formed in it between the respective first insertion slot and the box corner. The further engagement slot comprises angularly disposed slot portions 23, 24 with an apex 25 therebetween and is so disposed that, in the position of full insertion of the flap 16 into the insertion slot 18, at least one straight-linear portion 20 of the flap slot 20, 21, 22 has moved into a position of coincidence with engagement slot 23, 24 in the wall panel without the bowed portion 22 having moved past the apex 25 of the engagement slot in the wall panel 13.

The engagement slot 23, 25, 24 forms a readily deflectable resilient tongue within the wall panel 13, the tip 27 of the tongue being at 25 and pointing away from the box corner. In this specific form the tip may also be considered as pointing upwardly towards the top edge of the box.

In the illustrated configuration the slot portions 21 and 24 also move into coincidence, although this is not necessary for the function of the lock. The coincidence of the slot portions is preferably made to occur slightly before the lateral edge 26 of the end panel 13 abuts the face of the side panel or abuts the bead which is formed on the box inside at the corner fold line 17, in the event the latter is a crease score rather than a cut score (see in this regard FIG. 3 in which 217' is the bead).

In different words, the corner flap is permitted a slight amount of overtravel of its engagement slot portion with respect to the engagement slot portion 23 in the end wall.

If then, an outwardly directed force is applied at or near the X- marked spot on the wall panel 13 in order to move the apex tip 27 past the edge 22 of the engagement slot in the lock flap 16, the edge 23 moves freely past the edge 20 (which may have overtraveled) and no difiiculty is experienced in snapping the apex tip to the box outside, thus setting the lock by means of the tip 27 which thereafter acts as a safety catch.

When the box is subsequently filled the box side wall 12 and the flap 16 move back slightly and establish a lineal edge-to-edge engagement between edges 20 and 23.

There remains a minimum space D between the exposed edge 18 facing the corner and the oppositely facing edges 20, 23. As it is physically impossible for these oppositely facing edges to abut they cannot operate to limit the extent to which the corner flap 16 is insertable into the insertion slot. The amount of overtravel may, however, be limited in a convenient manner by arresting the edge 28 of the fiap 16 by the upper end of the slot 18, which may be fitted with a curved return 29.

The engagement between the engagement slots in the wall panel and in the corner fiap need not be of the lineal type. It may be effected by an interengagement of two slightly slanted edge portions.

This is illustrated in FIG. 2 which also shows that the three portions of the engagement slot may be portions of an arc of continuous, though not necessarily uniform, curvature.

A detailed description of the details of FIG. 2 may be dispensed with by application of reference numerals in the 200 series, in which the numerals used in FIG. 1 are preceded by numeral 2 and are applied to corresponding elements of FIG. 2.

The engagement slot in the corner flap comprises end portions 220 and 221 whose tangential directions are of different angular orientation. The engagement slot 223, 224 in the end wall 213 is upended with respect to the orientation of the corresponding slot 23, 24 in FIG. 1 and the tip 227 which points away from the box corner also points downwardly towards the bottom panel 11.

By application of a setting force at the X-mark in an outward direction the tip 227 is snapped to the outside, as seen in the left-hand portion of FIG. 2, and an engagement of the edges is formed at about the zone marked by arrows L-L.

FIG. 3 illustrates the manner in which the respective panels and flap are flexed. It is evident that the tab or lug 227 is protected by its recessed position between the edges 218 and 220 which face each other, but cannot abut, as they would in known designs in which the insertion slot also serves as engagement slot. The corner bead 217' of the corner fold line 217 is shown as nearly abutting the lateral edge 226 of the wall panel 213.

What is claimed is:

1. In a folding box comprising two wall panels articulated to a bottom panel and meeting at a box corner, one of the wall panels having a lock flap articulated to it at a corner fold line, said flap between foldable over, and insertable into an insertion slot in said other wall panel and in which the insertion slot is an angular slot defining an internal first wall tongue directed towards the box corner, the lock flap having an internal first engagement slot formed in it, the'improvement which is characterized in that there is formed in the other wall panel an angular second engagement slot between said insertion slot and the box corner, said second engagement slot defining an internal second wall tongue directed away from the box corner, said second engagement slot comprising two substantially straight-linear and angularly disposed portions and an apex portion between said straight-linear portions, said first engagement slot in the flap comprising at least one portion coinciding with a portion of said second engagement slot, said apex portion deviating from the central porton of said first engagement slot in the position of full insertion of said flap into said insertion slot, said angular second engagement slot being formed in said other wall panel in a location in which, in said condition of full insertion, at least a portion of said first engagement slot in the flap has moved at least into a position of coincidence with the engagement slot in said other wall panel without the apex portion having moved past said first engagement slot, the apex portion of the engagement slot in said other wall panel being adapted to be snapped from a position underlying the lock flap past an edge of the central portion of the flap slot into a position overlying the outside surface of the lock flap, in which position the apex of the internal wall tongue lies in substantially the same plane as the lock flap and faces away from the corner.

2. A folding box according to claim 1 in which the engagement slot in the flap comprises two substantially straight-linear portions and an apex portion therebetween which is shallower than the apex portion of the engagement slot in the said other wall panel.

3. A folding box according to claim 1 in which said second wall tongue which is directed away from the box corner also points away from the box bottom panel.

4. In a folding box comprising two wall panels articulated to a bottom panel and meeting at a corner, one of the wall panels having a lock flap articulated to it at a corner fold line, said flap being foldable over, and insertable into an insertion slot in the other wall panel, there being a first engagement slot in the wall panel between the insertion slot and the box corner and a further engagement slot in the lock flap, the improvement which is characterized in that said first engagement slot comprises two arms disposed at an angle with respect to each other and an apex portion between said two arms, said first engagement slot forming an internal wall tongue whose tip is said apex, the tongue pointing away from the box corner and towards said bottom panel, and in that said further engagement slot in said flap is of arcuate shape, the concave side of which faces the corner and is so disposed that, in the condition of full insertion of said flap into said insertion slot, at least a portion of one arm of the wall slot coincides with a portion of the flap slot and that the tip of said wall tongue cuts across the arcuate flap slot and may be snapped from an underlying position with respect to said lock flap past an edge of the arcuate slot into an overlying position.

5. A folding box according to claim 4 in which the insertion slot is an angular slot defining an internal wall tongue pointed towards the box corner.

References Cited UNITED STATES PATENTS 377,813 2/1888 Munson 2293S 1,462,009 7/1923 Higginson 22935 2,605,955 8/1952 Meller 22935 3,059,829 10/1962 Thompson 22935 DAVID M. BOCKENEK, Primary Examiner US. Cl. X.R. 

